Type 3EF Surge Limiters Rated voltage 3.6 to 15 kV, nominal discharge current 1 kA n Lower protection level than in the case of common arresters n The protection characteristic is relatively insensitive to steepedge impulse waves n Especially suitable for limiting n All-purpose solution for effective protection of high-voltage motors, independent of the system configuration HG21025b.eps switching impulse overvoltages Medium-Voltage Equipment Catalog Data Sheet HG 21.2.3 ⋅ 1999 Supersedes: Catalog Data Sheet HG 21.2.3 . 1991 HG21025.eps Type 3EF Surge Limiters Type 3EF1 surge limiter n Application n Protection for motors The task of type 3EF surge limiters is to restrict excessive overvoltages that might damage the windings of highvoltage motors. Such overvoltages can occur through the use of switchgear that has extremely fast dielectric recovery of the contact gap after the current zero crossing. These types of surge limiters have been designed for use in cable systems and are normally installed indoors. Type 3EF1 surge limiters are normally used in cable systems up to 15 kV. For station service systems of power stations and extensive cable systems type 3EF3 surge limiters are used having a higher absorption capacity and improved protection level. If the cable system is connected to overhead lines, a set of surge arresters must be fitted at each transition point, e.g. type 3EG/3EK. Surge limiters selected from the following table are recommended for the protection of motors with a starting current < 600 A. When unit-connected transformers are employed, the current on the switch side is the governing factor. n Construction and mode HG21010.eps of operation Type 3EF3 surge limiter 2 Siemens ⋅ HG 21.2.3 ⋅ 1999 The housing is made of plastic. Inside the housing there are gaps and non-linear resistors connected in series. The interior is hermetically sealed and there are screwed studs at each end for making the electrical connections. The series gap has a low sparkover voltage and, under normal circumstances, isolates the resistors from the supply system. The resistors are Siemens SIOV metal-oxide varistors which have a very sharply curved current/voltage characteristic. The resistance decreases in considerable overproportion to an increase in voltage and increases again similarly when the voltage decreases. As a result of these characteristics, the surge limiters respond very quickly to switching surges and restrict them to low values. Rated motor voltage to Surge limiters 3.6 kV 3EF1 036-0A 3EF3 036-0 4.8 kV 3EF1 048-0A 3EF3 048-0 7.2 kV 3EF1 072-0A 3EF3 072-0 12 kV n Dimension drawings Fig. 1 Types 3EF1 036-0A to 3EF1 072-0A 3EF3 120-1 n Installation The surge limiters can be mounted in any position, connected phase-to-earth. The value of rated voltage Ur marked on a surge limiter must not be exceeded in service at the place of installation. This also applies to all kinds of tests. When installing surge limiters ensure that the clearances between live parts or between live parts and earthed parts are not less than the minimum values specified (DIN VDE 0101). The earthing connection of the surge limiters is identified with the symbol . e Note: Surge limiters must be disconnected from the system before any voltage tests are carried out on the switchgear. Fig. 2 Types 3EF1 120-0A to 3EF1 150-0A Fmax = 10 N n Selection and ordering data Rated voltage1) Ur (rms value) Continuous operating voltage2) Uc Switching impulse sparkover voltage Ual (5/200 wave) Energy Residual absorption voltage Ures capacity with 0.5 kA impulse current (30/60 wave) kV kV kV kV Order No. kJ/kV rated voltage Weight approx. Dimension drawing kg Fig. 3EF1: indoor version 3.6 2.9 8 8 0.8 3EF1 036-0A 0.73 1 4.8 3.6 10 10 0.8 3EF1 048-0A 0.73 1 7.2 5.4 15 15 0.8 3EF1 072-0A 0.73 1 12 9 25 25 0.8 3EF1 120-0A 1.2 2 15 11 31 31 0.8 3EF1 150-0A 1.2 2 3 3EF3: indoor version 3.6 3.2 8 8 4 3EF3 036-0 3 4.8 4.1 10 10 4 3EF3 048-0 3.5 7.2 6.1 15 15 4 3EF3 072-0 4 7.2 4.9 12 12 4 3EF3 072-1 4 12 10.2 25 25 4 3EF3 120-0 5 12 8.2 20 20 4 3EF3 120-1 5 1) The rated voltage is the max. permissible power-frequency voltage which may occur at the mounting position of the limiter in case of an earth fault. 3 2) The continuous operating voltage is the max. continuous permissible power-frequency voltage to earth which may occur at the mounting position of the limiter during service. Fig. 3 Types 3EF3 036-0 to 3EF3 120-1 Fmax = 10 N Siemens ⋅ HG 21.2.3 ⋅ 1999 3 Conditions of Sale and Delivery Conditions of Sale and Delivery Subject to the General Conditions of Supply and Delivery for Products and Services of the Electrical and Electronic Industry and to any other conditions agreed upon with the recipients of catalogs. n The technical data, dimensions and weights are subject to change unless otherwise stated on the individual pages of this catalog. The illustrations are for reference only. We reserve the right to adjust the prices and shall charge the price applying on the date of delivery. Export Regulations In accordance with the present provisions of the German Export List and the US Commercial Control List, export licences are not required for the products listed in this catalog. An export licence may however be required due to country-specific application of the products. Relevant are the criteria stated in the delivery note and the invoice regaeding a possible export and reexport licence. Subject to change without notice. Dimensions Trademarks All dimensions in this catalog are given in mm. All product designations used are trademarks or product names of Siemens AG or of other suppliers. Bereich Energieübertragung und -verteilung Geschäftsgebiet Mittelspannung Postfach 3220 91050 Erlangen http://www.ev.siemens.de Siemens Aktiengesellschaft © Siemens AG 1999 Order No.: E50001-K1521-A231-A2-7600 Printed in Germany KGK 0299 3.0 4 En 100639 6101/U620